Hi,
I have been unable to reproduce your problem and unfortunately the logs do not provide really any indication on what happened, but it also appears based on the log output that is not the first build you have done for this OS seeing how the iso has already been mounted from a previous run. It is possible something went wrong during the first run.
If you could run from a clean install of Studio or perhaps try a later dot release of RHEL such as 6.1 to see if the problem persists or if you are able to use 6.3 that would be ideal.